We once thought Mars had canals built by an advanced society. We’ve come a long way since then, but there is still much to discover, finds Leah Crane
1 July 2020
NASA’s Perseverance rover will soon look for signs of life on Mars
The Sirens of Mars: Searching for life on another world
IF YOU look up on a clear night, you might spot a light brighter than all the others, not twinkling like a star, but floating serene and reddish-tinged in the sky. Across history, many have gazed at Mars and imagined what its distant shores might hold. Some have even sent spacecraft up there to find out.
In her book The Sirens of Mars, Sarah Stewart Johnson tells the story of the Red Planet and those who have sought to understand it, from Herodotus and Euclid to NASA and its Curiosity and Perseverance rovers, with the author herself slotted in between.
The tale begins before Mars was even understood to be a place, when it was just a light in the sky. It then moves on to when scientists thought that Mars could be truly the twin of Earth, when apparent lines on its surface were taken to be the canals of an advanced society. Even after discovering they weren’t canals, people still thought they could be signs of vegetation, the signature of a green and thriving planet.
At the point Stewart Johnson reaches the first space missions to fly by Mars and their failures to spot any obvious signs of life, the disappointment is palpable. The narrative feels as if it is building towards a big revelation, maybe even the discovery of living organisms on Mars. Those who have studied the planet for a long time know intimately the roller coaster of emotion it has caused.
Stewart Johnson has made Mars her life’s work. She is from a space-loving family, making her career choice seem inevitable. The book is part memoir, part history, part education, and the three flow together so smoothly you might not even realise how much you are learning about Mars.
At one point, she describes crater walls as “reveal(ing) layers that had been stacked like the pages of a closed book, one moment in time pressed close against the next”. She manages to press moments in time together as closely as the sedimentary rocks on Mars, revealing its history just as the rocks do.
“Mars may not be quite as arid and dead as we once thought, but rather it has water hiding everywhere”
As much as that history contains many disappointments, from the revelation that the canals of Mars aren’t real to the understanding that there is unlikely to be life on the surface, it is also optimistic. There are many joyful moments, such as when scientists realised that Mars might not be quite as arid and dead as we once thought, but rather it has water hiding everywhere.
Those moments are what propel the story forward and what drives Stewart Johnson to keep travelling to some of the most extreme and barren environments on Earth to grasp at the possibility that there may yet be life on Mars that looks nothing like it does here on Earth. “We are still struggling to contend with the truly alien, to recognize and interpret signs of ‘life as we don’t know it’, ” she writes.
The Sirens of Mars comes at an exciting time: Mars researchers have more information now than at any other point in history, and NASA’s Perseverance rover, scheduled to launch this month, will surely bring a wave of discoveries when it collects rock and soil samples in its search for signs of ancient life. Yet as the interest in Mars grows, with many nations and companies working on missions to its surface, researchers’ efforts to understand it become increasingly urgent.
As Stewart Johnson writes: “The next decades are thus critically important for the search for life because the window to explore an untrammeled planet – a pristine record of the past – is closing.”
In the end, the book tells you what anybody who has studied science learns as they move from one school year to the next: the more we know, the clearer it is that what we thought we knew before was wrong. However, as Stewart Johnson so clearly describes, the journey of understanding where we were wrong propels us ever forward to explore.
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